A conventional baker's oven comprises a number of stacked oven compartments with individual oven doors at the front. Each level of the oven includes two side by side compartments, which each have a fixed shelf onto which baking trays or bread pans or a like can be loaded.
The oven compartments are heated by electric heating elements mounted bottom and top of each compartment. The heating elements are formed as single heating units comprising a number of parallel arms connected in series by U-shaped elements. The parallel arms extend from the oven door to the rear of the compartment and are spaced across the width of the oven.
The top and bottom heating elements can be separately controlled to vary the heat distribution within the oven. For certain types of baked goods, it is advantageous to supply the heat predominantly from the bottom of the oven. The bottom heating elements of conventional baker's ovens are usually more or less uniformly distributed over the floor of the oven to provide a uniform distribution of heat within the oven. According to conventional baking practice, it is important that a constant temperature is maintained throughout the baking cycle, thus preheating the oven, or allowing the oven to cool prior to loading with product is important. Typically the oven temperature must be kept within 10° C. of an ideal temperature.
It is known to use a timer to activate the oven prior to the arrival of the baker at the start of the day, so that the oven is preheated when the baker arrives. While the use of a timer effectively presents an oven at a predetermined temperature at a time set many hours earlier, there are risks (e.g., of fire) associated with activating unattended ovens. Commercially available Multi-deck, Setter ovens, and other such ovens with multiple baking chambers within one chassis, may be capable of baking many different products at the same time. However, it is commercially accepted that these ovens need to be pre-heated to, or above, recipe temperature before loading each product. As there is no fan assistance in most conventional ovens, the heat is typically difficult to control, and the baker must often be familiar with each oven's characteristics to achieve acceptable results.
Different bakery products require different baking temperatures. Therefore the baker's production schedule is complicated, and the oven utilization is reduced by having to pre-heat/pre-cool an oven prior to baking. The production schedule must be changed so that the oven temperature closely matches the requirements of the next product to be loaded. In busy bakeries, there is often the need to break the usual production cycle (due to rejected product, unexpected orders etc.) and there is also the issue of inexperienced staff needing to run ovens at short notice. Even for the most experienced operator, the issues involved in obtaining the most efficient production schedule are often at odds with what the store's customer's demand for fresh full variety of product.
A particular problem with controlling oven temperature is “heat over-run”. Heat over-run stems from the thermal inertia of the heating system. Typically the heating elements are much hotter than the air in the oven. Heat is thereby transferred from the elements to the air and is in turn transferred to the bakery product in the oven. Heat over-run occurs after the oven is unloaded and the bakery product is removed. After the bakery products are removed, even if the heating elements are deactivated, heat stored within the elements is transferred to the air within the empty oven. This results in a very hot oven. This heat is not only wasted but results in considerable inefficiency in that the oven may well be too hot for the next batch of products to be loaded, meaning that the oven must then be precooled for the next batch. One approach to the issue is to gradually reduce the power to the heating elements as the oven air temperature approaches a required baking temperature. This means that the elements are not as hot as they might be when the oven is unloaded.
Objects of the present invention include to reduce oven preheating/precooling requirements or at least provide alternatives to existing arrangements in the marketplace.